Previous experiments in our laboratory have described the sympatho-adrenal regulation of the heart in unanesthetized non-human primates (Macaca mulatta) during exercise and emotional (i.e., Pavlovian) conditioning. This project extends these efforts by making comparable observations on the hearts of intact monkeys during behavioral testing before and after experimental myocardial infarction (EMI). The objects of the study are: 1) to describe the effects of EMI upon cardiovascular responses to stress in monkeys and 2) to determine the role exercised by the autonomic nervous system (ANS) in cardiac control following myocardial infarction. Monkeys are being conditioned to one minute tone followed by an unavoidable electric shock. After repeated exposure to this paradigm presentation of the tone elicits a characteristic cardiovascular response which can be quantitatively analyzed using data acquistion techniques developed for use in this project. An infarction of a discrete area of the myocardium is then produced in the unanesthetized animal by occluding blood flow through a portion of the left anterior descending coronary artery. Continued presentation of the behavioral tests permits us to describe the effects of the infarction upon the conditional responses. The contractile properties of the surviving and infarcted muscle can be selectively examined using isometric strain gauge arches implanted on appropriate areas of the left ventricle. Results to date support the hypothesis that the ability of the heart to respond during stress is compromised by EMI but that the autonomic nervous system acts to partially compensate for this loss. The ANS may also be involved in the genesis of cardiac arrhythmias which have been observed during emotional conditioning after EMI. We suggest that this preparation will be of considerable value for testing pharmacological and behavioral treatments for clinical myocardial infarctions. BIBLIOGRAPHIC REFERENCES: Randall, D.C., M.P. Kaye, W.C. Randall, J.V. Brady & K.H. Martin. Response of the primate heart to emotional stress before and after cardiac denervation. Amer. J. Physiol., 230: 998-995, 1976. Randall, D.C. & D.M. Hasson. Immediate cardiovascular effects of coronary artery occlusion and emotional stress in monkey. Physiologist, 19: 334, 1976 (abstract).